docs: add links to other language versions of README

[dowithless]

Added language selection links to the README for easier access to translated versions: German, Spanish, French, Japanese, Korean, Portuguese, Russian, and Chinese.

After the README was updated, my previous pull request (https://github.com/tensorzero/tensorzero/pull/2413) had merge conflicts. I resolved the conflicts, synchronized the translation content with the latest README, and am now submitting this updated PR.

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[!IMPORTANT] Added language selection links to README.md for multiple translations, enhancing accessibility.

• Documentation:
  • Added language selection links to README.md for German, Spanish, French, Japanese, Korean, Portuguese, Russian, and Chinese translations.

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[dowithless]

Preview the updated links in my forked repository: https://github.com/dowithless/tensorzero/tree/patch-2

[GabrielBianconi]

I don't think it's necessary to add these links. People who want translations can use their browser's built-in translations or go to their preferred website. I made some small fixes to the README in the meantime, so we can merge.